Viva Las Vegas - 1976 Chevrolet Cosworth Vega

Chevrolet's Cosworth Vega makes 110hp seem like plenty

Feature Article from Hemmings Classic Car

Jim Ruby pulled from his Rensselaer, New York, garage an aluminum box, finned on one side, smooth on the rest. It felt heavy. The metal of the box had dulled from 30-plus years of storage. A multi-connection plug sprouted from the finned side; a label on one of the smooth sides read "Bendix Electronic Fuel Injection Division."

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"Know what this is?" he asked. "It's the computer for a Cosworth Vega. You can't get them anywhere anymore, so I always carry a spare with me."
He then recalls the one and only time his 1976 Cosworth Vega stranded him: On his first major trip with the Cosworth, his stock electronic control unit started to flake out. A friend loaned him a spare ECU, which Jim plugged in, but left dangling under the dash. A couple states into the trip, he hit a rumble strip on the highway, causing the ECU to come unplugged and his Cosworth to come to a dead stop in between banks of 18-wheelers.
With that in mind, do I really feel like taking this Cosworth for a spin to get the requisite driving impressions? Fortunately, I don't have much time to contemplate the situation before I find myself on Interstate 90 outside of Albany, New York, keeping the wheel straight as I zip by a semi and wondering whether the ECU and its plug sit secure in their spot behind the dash.
What the Cosworth doesn't require in concentration, it requests in exhilaration. Jim said he loves the go-kart feel of the Vega, and it's easy to understand his comparison. The Cosworth truly feels like a subcompact car, as any car built on a 97-inch wheelbase should, but that's not necessarily a bad thing. The tiny "sport" side mirror, all but useless on larger cars, mounts closer to the driver's eyeballs in the Cosworth and thus actually provides a decent rear view. The fenders seem close enough to touch, as does the rear hatch glass, and the road feels much closer, more personal. But you don't feel like you have to fold yourself in and out of the doors, thanks to their length. And you don't feel like a pair of swim trunks stuffed in a suitcase when sitting in the bucket seats, likely due to the white interior and the lack of window tinting, which makes the windshield seem much more panoramic.
The Cosworth package might also have something to do with the go-kartness of this particular Vega. Larger 1-inch front and 13/16-inch rear anti-roll bars, heavy-duty 350-pound-per-inch front springs, 155-pound-per-inch rear springs, torque arm rear suspension and the lack of power steering all combine to provide a direct connection with the road, for better or worse. For better because, once at speed, the Cosworth simply goes where you point it without any noticeable understeer or oversteer and without rolling over. Just point and go. Shoot and ask questions later. For worse because the pressure-cast aluminum wheels, an industry first, can't be straightened easily or cheaply, and thus on Jim's car wobbled at around 70 miles per hour. The wobble, which simply required keeping both hands on the wheel, smoothed out around 75 mph, but returned with a vengeance above 80, shaking loose anything not bolted down.
Again, I ask myself, what am I doing in this car?
I half-expected a dog of an engine before slipping behind the wheel. Not that the HEI-ignition, dual overhead-camshaft, pentroof-headed all-aluminum four-cylinder with its electronic fuel injection didn't look spectacular in that engine bay. But 110 horsepower just didn't seem a lot, even in a 2,549-pound car. Minivans nowadays have double that.
The men behind the Cosworth Vega's four-cylinder certainly hadn't aimed that low. Jim Musser and his staff originally designed the base Vega's single-overhead-camshaft carbureted four-cylinder engine--what GM designated the L-13 or the L-11, depending on whether it had a one- or two-barrel carburetor, respectively--using a die-cast aluminum block and iron head, but without the steel cylinder sleeves that had been considered a necessity in earlier aluminum-block engine designs. Instead, the block's high silicon content (17 percent) and a new electro-chemical etching process allowed the pistons to ride on the harder silicon, rather than the softer aluminum.
At the request of John DeLorean, Chevrolet's general manager at the time, Musser invited Keith Duckworth of Cosworth Engineering to evaluate the engine for a potential racing version. Duckworth accepted, and in 1969, after signing a contract with Chevrolet, Cosworth received a batch of prototype Vega L-11 engines to work with. Cosworth Chief Engineer Mike Hall then began work on the racing version, which Cosworth designated the EAA.
To meet Formula 2's 2-liter (122-cu.in.) displacement limit, Hall and his engineers specified a destroked 3.160-inch crankshaft (from the stock Vega's 3.625-inch crankshaft), but kept the same 3.501-inch bore for a total displacement of 121.7 cubic inches. They then designed a new aluminum head featuring dual overhead camshafts, 16 valves, crossflow design and pentroof combustion chambers. By March 1971, the first experimental EAA hit the dynamometer, and by September 1971, two others joined it, all producing about 270hp at 8,500 rpm.
Despite the potential of the engine, Cosworth later viewed the EAA as a failure. In the company's official information packet in 1988, as reproduced on cosworthvega.com, company spokesmen described the EAA as a "stumbling block" and a "debacle."
"The first road car to carry the Cosworth name did not enhance any reputations," Cosworth spokesmen wrote. "It was not the engine which was at fault, only the block, but that tends to be somewhat critical and the whole episode fated before it began. Hundreds of blocks were being delivered, many failing a pressure test Cosworth devised for them and littering up the place while a solution was found. It never was."
Hall watched as many of the test engines cracked just below the cylinder bores, splitting completely into two in at least one instance. Cal Wade, an engine design engineer for GM, had served as the liaison between Chevrolet and Cosworth and had attempted to provide stronger blocks for the EAA program, but as Cosworth Vega historian Duke Williams noted, "Block strength was not an issue on the 5,500 rpm production engine, but it was an issue when revs were pushed beyond 8,500 in the search for more power."
Cosworth thus abandoned the EAA project and never raced the engine in Formula 2, though the EAA did compete in Chevron chassis in a few local series in England and South Africa.
By this time, the Vega had entered the American market and was already showing signs of turning into a flop from engineering, production and sales standpoints. Lloyd Reuss, then Chevrolet's chief engineer, believed that a street version of the EAA might help improve the Vega's image. After all, Chevrolet had secured the rights to use the Cosworth name on a limited-edition Vega when Duckworth signed that contract.
According to Williams, the task of engineering the EAA for production use fell to Cal Wade, who prepared all-new part drawings based on the EAA design.
"Essentially, the cylinder head and its components were completely redesigned at the detail level," Williams said. "One of the major changes was upsizing many of the fasteners. For example, most 1/4-inch cap screws were replaced with 5/16-inch cap screws. All new tooling was produced and the aluminum castings rendered by the Winters Foundry."
Though Hall recommended several design changes to the block, Williams said that Wade could not convince the folks at headquarters to make the alterations because the blocks held up fine in normal production use and thus didn't warrant all-new casting dies.
While fuel injection was certainly underutilized--though not necessarily new--by that point, electronic fuel injection had only appeared once before on American production cars, on a handful of 1958 Chrysler products (HCC #1, October 2004). In the intervening decade-plus, Bendix worked out the kinks in its EFI system, so Wade designed an intake and induction system around a Bendix-supplied EFI system (using a few off-the-shelf Bosch components).
Chevrolet chose its Tonawanda engine plant as the main assembly point for the Cosworth four-cylinders and assigned about a dozen engine builders to assemble the engines by hand, away from the assembly line. Chevrolet would then ship the engines to its Lordstown, Ohio, assembly plant to be installed in Vega hatchbacks. Reuss projected a 1974 debut for the engine, and initial plans projected output at about 170 gross horsepower, or about 130 net horsepower.
However, the test engines showed signs of burning exhaust valves in the Environmental Protection Agency's 50,000-mile durability test. Bill Howell, then of Chevrolet's Product Promotion Engineering department, spent a good amount of time with the Cosworth engines on the dynamometer before the test and said afterward that the engines failed the test because one of the development engineers retarded the timing on the test engines to make sure they passed the emissions portion of the test. That plan backfired (no pun intended) and the retarded timing caused the exhaust valve failures.
So introduction would have to wait for another year, when Chevrolet returned to the test with a more conventional ignition curve, a new emissions system and a catalytic converter. By this time, horsepower tumbled to 110.
"The Achilles heel for the production Cosworth Vega engine was the rapidly tightening emission requirements and the crude emission control technology of the time," Williams says. "The early Seventies was the absolute worst time in the history of the automobile to be developing a high-performance engine package."
The engine, along with a four-speed transmission, a heavy-duty radiator, gold painted aluminum wheels, an engine-turned aluminum gauge panel and special striping and decals, formed the Z09 Cosworth Vega Special Performance Equipment package. Chevrolet launched the Cosworth Vega as a separate model with a $5,915.60 price tag (more than double the base Vega hatchback) on April 17, 1975. With a few minor changes--most notably the addition of eight exterior colors to 1975's black-only palette and a five-speed transmission to the option list--the Z09 package continued for 1976, but Chevrolet brass killed the option in July of that year.
One hundred ten horsepower got me around the semi trailers and up to shudder speed easily enough. Jim told me he once had the Cosworth up to 110 mph, but I didn't see how that was possible without a long, uninterrupted downhill. Or earmuffs. I was shifting the Saginaw four-speed at 4,000 rpm and cruising at highway speeds at almost 3,000 rpm. Utilizing the maximum engine horsepower meant running the engine up to 6,000 rpm or higher. Typical mid-1970s build quality would've had the Vega rattling like sabers over Swaziland as we approached the 6,500 rpm redline. Because all the power lies up in that stratosphere--and because the engine, at peak, develops just 107-lbs.ft. of torque at 4,500 rpm--starting line grunt felt noticeably absent.
The optional Borg-Warner T-50 five-speed transmission offered in 1976 did have an overdrive fifth gear, but Jim said the synchronizers on that transmission had a tendency to weld themselves together somewhere around 30,000 miles--usually waiting for highway speeds to do so. (Williams notes that the T-50 actually tended to fail when first gear seized to the transmission mainshaft.) The four-speed in Jim's car, though it had appropriately spaced gears and the shifter snapped smartly in and out of gear, required significant pedal effort, which Jim attributed to poor factory lubrication of the throwout bearing, another common Cosworth malady. (Again, Williams notes that the clutch cable's routing actually causes the stiff clutch.)
But the brakes felt good, the seats felt good and the Vega handled corners better than it should've. All of this in a car that still wore its original interior, three-quarters of its original paint and ran through an entirely untouched drivetrain.
To many folks, the Vega remains an eternal punchline. The Cosworth, though, earns it at least a little relief from the hyenas.
Owner's view
"I had a few Vegas in the early '70s, including a 1971 that I bought when it was a year old. I really liked the blue metallic color they had, so when I found out that Chevrolet was going to build the Cosworth Vega in that color, I went down to the dealership to order a 1977 Cosworth in blue metallic. The dealer told me that they weren't going to make a 1977 Cosworth, though, and tried to find a '76 for me in different colors, but couldn't come up with one in blue metallic.
"It wasn't until 1988 that I saw this white Cosworth over in Massachusetts. It had been hit real hard by a Dodge Dart Swinger and probably should have been totaled, but a body shop tried to fix it and did a poor job. Surface rust had started to come up and the panels were barely welded in, so I bought it and completely rebuilt the side of the car, then painted it back in its original white.
"A lot of guys tell me just to stick a V-8 in it, and I could, but I like the way it handles with a four-cylinder, which is just perfect for all the curvy back roads around here."
- Jim Ruby
What to Pay
Low: $3,500
Avg: $6,000
High: $10,000
PROS:
Unique
Decent performance
Handles exceptionally well
CONS:
Shakes and rattles
It's still a Vega at heart
Could've performed better
Club SCENECosworth Vega Owners Association
P.O. Box 5864
Pittsburgh, Pennsylvania 15209www.cosworthvega.com
Dues: $30/year; Membership: 406
Specifications
Base price: $6,065.60
Options on car profiled G80 Positraction, $48
ENGINE
Type: DOHC 16-valve L-4, aluminum block and cylinder head
Displacement: 121.7 cubic inches
Bore x Stroke: 3.501 x 3.160 inches
Compression ratio: 8.5:1
Horsepower @ rpm: 110 @ 5,600
Torque @ rpm: 107-lb.ft. @ 4,800
Valvetrain: Mechanical valve lifters with shim-over-bucket lash adjustment
Main bearings: 5
Fuel system: Bendix electronic fuel injection, electric in-tank feed pump with external high-pressure pump
Lubrication system: Pressure, gear-type pump
Electrical system: 12-volt
Exhaust system: Single, with stainless steel header and catalytic converter
TRANSMISSION
Type: Saginaw four-speed manual
Ratios 1st: 3.11:1
2nd: 2.20:1
3rd: 1.47:1
4th: 1.00:1
Reverse: 3.11:1
DIFFERENTIAL
Type: GM 7.5-inch with Positraction limited-slip differential
Ratio: 3.73:1
STEERING
Type: Saginaw recirculating ball, non-power-assist
Ratio: 22.5:1
Turns, lock-to-lock: 4.4
Turning circle: 33 feet
BRAKES
Type: Hydraulic, non-power-assist
Front: 9.88-inch disc
Rear: 9.50-inch drum
CHASSIS & BODY
Construction: Steel unibody
Body style: Two-door hatchback
Layout: Front engine, rear-wheel drive
SUSPENSION
Front: Independent, unequal length A-arms; 350-pound-per-inch coil springs; Gabriel Strider shock absorbers; one-inch diameter anti-roll bar
Rear: Trailing arms, torque arm and Panhard bar; 155-pound-per-inch coil springs; Gabriel Strider shock absorbers; 13/16-inch diameter anti-roll bar
WHEELS & TIRES
Wheels: Cosworth package pressure-cast alloy
Front/Rear: 13 x 6 inches
Tires: Uniroyal Tiger Paw Touring TA
Front/Rear: P185/70R13
WEIGHTS & MEASURES
Wheelbase: 97.0 inches
Overall length: 176.4 inches
Overall width: 65.4 inches
Overall height: 50.0 inches
Front track: 54.8 inches
Rear track: 53.6 inches
Shipping weight: 2,549 pounds
CAPACITIES
Crankcase: 4 quarts with filter
Cooling system: 6.8 quarts
Fuel tank: 16 gallons
Transmission: 3 pints
Rear axle: 2.75 pints
CALCULATED DATA
Bhp per c.i.d.: 0.90
Weight per bhp: 23.17 pounds
Weight per c.i.d.: 20.96 pounds
PRODUCTION
Of 3,508 total Cosworth Vegas, Chevrolet built 1,447 in 1976.

This article originally appeared in the December, 2007 issue of Hemmings Classic Car.